10/31/2005

MAS863 | Fall 2005

Assignment:

• Make serial and in-circuit programming cables

• Add a Zener diode to the hello-world circuit to receive RS-232

• Revise the microcode to echo characters

• Add an LED and blink it when a character is received

• For (lots of) extra credit write the microcode for a SLIP Web server
    (HTTP (TCP) or THTP (UDP) / IP)
   

Project:

1. The cables were made last week - the techniques for molex connectors are critical in saving time, look for cable guru info to show up soon.

2. Design PCB using EAGLE - It was very difficult to get the Nets attached to the AT13 pins.  Several attempts were necessary when generating the Gerber file, my devices kept showing up in CAM.py.  Turning off all layers except top, pads and vias seem to solve the problem.

3. I stepped up the speed when machining the PCB with the Modela.  At an X-Y speed of 5, the bit tip snapped about half-way through rastering.  Slowing down to 3 completed the board - we will see how long the bit life will be at that speed.  Stuffing the board  - polarity on the diodes is the only new trick with this board.  Cathode on the Zener is identified by a stripe.

4. Programming:

• I used scripts that Jesse had modified to test the board.  Fortunately the board tested good the first time.

• I spent an inordinate amount of time downloading the AVR programs to my computer.  I had limited success with the AVRStudio4 suite, I was able to develop .asm files.  However getting the hardware to work with my laptop is an incomplete chore at this point.